A Research On On-line Test Of LVDT Demodulator Circuit Based On SBST

The LVDT demodulation circuit chip is a crucial functional module of the master controller in aircraft engine system.With the increase of the complexity of aircraft engine system and the continuous improvement of the deep submicron technology in chip manufacturing,the LVDT chip is much more vulnerable to various faults.To enhance the overall reliability of the aircraft engine control system,effective on-line testing methods are urgently needed and test approach should be considered during the design of the chip.This paper researches the on-line test approach targeting the LVDT demodulation circuit based on SBST approach.After analyzing several existing on-line test approaches of integrated circuits,this paper presents a test structure based on software self-test.The microprocessor is appended to apply test pattern,control test flow,collect test response and accomplish on-line test diagnosis.Test scheduler program is stored in the ROM of the microprocessor,and the corresponding test patterns and ideal responses are stored in the RAM.Based on the instructions of the microprocessor,test control and test scheduling program can realize the on-line test of each functional module of the LVDT demodulation circuit.To achieve high fault coverage with a small-scale test data,the test patterns of functional modules are generated by an ATPG tool called TetraMAX while the memory module is tested by improved March C+ algorithm.The test structure based on SBST has high extendibility and flexibility.Therefore,it can easily be modified when the design and parameters of the LVDT chip changes.In addition,this paper presents a microprocessor self test approach to test the microprocessor which is the key module of on-line testing structure.Test patterns are generated for every functional module of the microprocessor with specific algorithm and the bottom-level faults can be tested through CPU instruction programs.With the proposed testing approach,this paper establishes a SBST test system targeting the LVDT demodulation circuit that has filter,controller and other modules.The whole system was simulated in the Spartan6 FPGA evaluation platform and Design Complier software to verify the correctness of online test circuit and analysis the performance.